Within the minimal brain dysfunction (MBD) population are two types who display faulty learning behaviors akin to those seen in monkeys with inferotemporal and dorsolateral frontal lesions, respectively. The "temporal types" seem deficient in search strategies (selective attention), whereas the "frontal types" fail to benefit normally from outcomes of their actions (implications). The former are nonhyperactive learning disabled (LD) children and the latter are hyperactive-impulsive but without marked retardation in academic skills. These two types (20 subjects in each group) will be contrasted with 20 controls on a problem solving task similar to one utilized by K.H. Pribram. The children will have to search our from several cues the positive stimulus and then must stick with this choice until it is no longer rewarded. After switch, they must search again for the new positive cue, etc. Subjects will be male Caucasians, aged 8-9 years. Background and psychological test data will include home stimulation potential, role-taking ability, introversion-extraversion, and locus-of- control measures as well as measures of intellect and achievement. Compared to non-hyperactive LD types, hyperactives are predicted to be extraverted, poor at role-taking, and unlikely to assume responsibility for their failure; their homes will offer more cognitive stimulation but daily routines will be less structured and regular. Autonomic levels (arousal) during problem solving will show controls greater than hyperactives greater than LD subjects. Response latencies will be similarly ordered and will be most variable in hyperactives. Average evoked responses (particularly the later components) should be of greater amplitude and shorter latency in hyperactive than LD than control subjects, reflecting neurophysiological immaturity in the first two groups. Differences in learning styles, if demonstrated, will point up the need for more specific management and pedagogical prescriptions for LD and hyperactive children.